US2462087A - Electron discharge device of the velocity modulation type - Google Patents

Electron discharge device of the velocity modulation type Download PDF

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Publication number
US2462087A
US2462087A US588207A US58820745A US2462087A US 2462087 A US2462087 A US 2462087A US 588207 A US588207 A US 588207A US 58820745 A US58820745 A US 58820745A US 2462087 A US2462087 A US 2462087A
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electrons
resonator
apertures
electron
electron discharge
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US588207A
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English (en)
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Fremlin John Heaver
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International Standard Electric Corp
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International Standard Electric Corp
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J25/00—Transit-time tubes, e.g. klystrons, travelling-wave tubes, magnetrons
    • H01J25/02—Tubes with electron stream modulated in velocity or density in a modulator zone and thereafter giving up energy in an inducing zone, the zones being associated with one or more resonators
    • H01J25/22—Reflex klystrons, i.e. tubes having one or more resonators, with a single reflection of the electron stream, and in which the stream is modulated mainly by velocity in the modulator zone
    • H01J25/28—Reflex klystrons, i.e. tubes having one or more resonators, with a single reflection of the electron stream, and in which the stream is modulated mainly by velocity in the modulator zone in which the electron stream is perpendicular to the axis of the resonator or resonators and is pencil-like before reflection

Definitions

  • the present invention relates to electron discharges devices, and especially to those of the electron velocity modulation type, and is principally concerned with means for preventing the introduction of excessive noise which may occur under certain conditions of operation of these devices.
  • Velocity modulation devices may be operated by single transit, that is, so that each electron makes only one journey across the device and is then collected by an electrode; or they may be operated by reflecting the electrons back from an electrode after the first transit, so that they make at least another journey through the device in the reverse direction before being collected.
  • the principal object of the invention is to provide a construction for an electron discharge device in which the cause of the excessive noise which is liable to occur with operation by electron reflection is partly or wholly removed so that the necessity for critical adjustments is avoided.
  • an electron discharge device comprising means for projecting a beam of electrons in one direction through a structure, and means for preventing electrons reflected back in the reverse direction through the structure from returning to the source of the beam.
  • an electron discharge device comprising means for projecting a beam of electrons through a passage in a resonator, and for reflecting them back again through the same passage, and means for preventing the reflected electrons from emerging from the passage at the end into which the beam is projected.
  • the invention consists in an electron discharge device in which a co-axial line resonator is excited by projecting a beam of electrons through the resonator, comprising means for reflecting the beam back'across the resonator in the reverse direction, and means for causing the resonator to collect the electrons as soon as they have completed one return journey across the resonator.
  • the invention may also provide an electron discharge device in which electrons are projected in a beam through a resonator and are reflected back again in the reverse direction through the resonator, comprising means for dividing the beam into a number .of separate pencils and means for collecting electrons returning in the spaces between the pencils whereby materially to reduce the number of to-and-fro journeys made by the electrons before collection.
  • Fig. l is a diagrammatic cross-section of an electron velocity modulation device of the coaxial line type to show the path of the electron beam through the resonator;
  • Fig. 2 is a diagrammatic vertical section of the device to indicate the path of a single electron passing backwards and forwards through the resonator.
  • Fig. 3 is a diagram similar to Fig. 2 of a device according to the invention to show the double transit path of a single electron;
  • Fig. 4 is a cross-section diagram like Fig. 1, but corresponding to Fig. 8;
  • Fig. 5 shows in exploded perspective form the elements of a device according to the invention.
  • Fig. 6 shows a modification of Fig. 5.
  • Fig. 7 is a diagrammatic assembly View of the tube shown in Fig 5.
  • the electron beam is projected from the cathode I through the control electrode 2 and across the co-axial line resonator 3 to a reflecting electrode 2.
  • the resonator 3 will usually be maintained at a positive potential with respect to the oathode, and electrodes 2 and A will be mainta ned at negative potentials.
  • the magnetic field 1s m the same direction as the beams as indicated by the dotted lines and arrows.
  • the electrons leaving the middle of the oathode will be constrained to follow approximately the magnetic lines of force, which will keep them in the middle of the slot through the resonator. They will be reflected by the electrode 4 and will follow nearly the same path on their return. After this second transit it is obvious that many of them must have lost ener y, otherwise the oscillation of the resonator could not be maintained. A large'proportion of the electrons will therefore be unable to reach the cathode and will be reflected back again through the system. If, as is usual, the magnetic field is strong, they will never be able to reach the sides of the slots.
  • the electron velocity perpendicular to the beam must be equivalent to the energy of 1'70 electron volts to enable them to reach the sides of the slot.
  • the electric field will not be wholly parallel to the beam, but will have small components transverse thereto. The effect of these small transverse components acting with the magnetic field is to deflect the electrons perpendicularly to the plane of the paper by small amounts, and the direction of displacement is likely to be different near the control electrode from that near the resonator.
  • FIG. 2 shows a typical track of an electron gradually displaced downwards in this way.
  • Figs. 3 and 4 show how according to the invention, the electron may be collected after two transits, one in each direction.
  • the slot in the resonator opposite the cathode is closed by a strip 5 attached to the resonator and provided with a number of small apertures I spaced apart in a line conforming with the slot, in order, to divide the electron beam into a number of small separated pencils.
  • the control electrode 2 should at the same time be modified to direct the electrons through the apertures so that as few electrons as possible are lost by being collected on the surfaces between the apertures.
  • This control electrode might be a wire grid having a pitch equal to the distance between the apertures, or it might be substantially a duplicate of the strip 5, as shown in Fig. 3. In either case, the control electrode should preferably be placed close to the cathode and should be registered with the strip 5 as indicated in Fig. 3.
  • a further advantage of the system is that the returned electrons cannot penetrate into the space between the cathode and the resonator, and cannot, therefore, afiect the emission current. This was a source of difliculty in the devices of existing type as shown'in Figs. 1 and 2, in which the space charge in this region is found to be much affected by the reflected electrons, so that considerable change in the current occurs at the commencement of oscillation, sometimes leading to instability,
  • Figs. 5 and 6 show in more detail the arrangements of the various parts in two embodiments of the invention.
  • the control electrode 2 is in the form of a wire grid, the wires being spaced the same distance apart as the slots in the strip 5.
  • the deflecting plates 6 are shown behind the resonator 3, and the reflector i is a plate bent to form three sides of a polygon. 8 is a screen to absorb electrons emitted backwards from the cathode, and 9 is the lead 1for the central conductor of the co-axial resona- Fig. 6 shows an arrangement in which the deflecting plates are omitted, and in which the control electrode is a plate perforated with apertures similarly to the plate 5.
  • the reflecting electrode 4 is in this case a flat plate.
  • control electrode may be used in eitherof the devices shown in Figs. 5 and 6.
  • Fig. 7 shows an assembled structure of Fig. 5 within an envelope, l0.
  • parts corresponding to those in Fig. 5 have been given the same reference numbers.
  • the device according to the invention described with reference to Figs. 3, 4 and 5 is one which allows the passage of the electrons in one direction, but which prevents the electrons travelling in the opposite direction from returning to the neighborhood of the cathode or control electrode.
  • An electron discharge apparatus of the electron velocity modulated type comprising a cavity resonator having an entrance aperture and an exit aperture in the wall thereof, said apertures being in alignment on opposite sides of the axis of said resonator, means adjacent said entrance aperture for producing and projecting a beam of electrons through said apertures,
  • An electron discharge apparatus according to claim 1, wherein said means for producing and projecting a beam of electrons comprises a cathode, said cathode being disposed adjacent to, and in alignment with, the apertures of said cavity resonator.
  • An electron discharge apparatus wherein the means for producing and projecting a beam of electrons comprises a source of electrons disposed adjacent to, and in alignment with the apertures of said cavity resonator, and a control electrode, disposed intermediate said source of electrons and said cavity resonator.
  • An electron discharge apparatus wherein the means for reflecting said beam of electrons comprises a reflector electrode, positioned opposite the exit aperture of said cavity resonator 5.
  • An electron discharge apparatus wherein the means for producing a field and for deflecting said beam of electrons comprises a pair of deflecting electrodes parallel to and spaced from each other and positioned intermediate said cavity resonator and said means for reflecting said beam of electrons, said deflecting electrodes also being positioned on opposite sides of the path of said beam of electrons.
  • said cavity resonator comprises a plate attached to the wall thereof, adjacent said means for producing and projecting a beam of electrons, said plate having at least one aperture therein, said aperture constituting the entrance aperture of said cavity resonator, and another portion of said plate constituting the means for collecting said beam of reflected electrons.
  • An electron discharge apparatus of the electron velocity modulated type comprising a cavity resonator having a plate attached to the wall thereof, said plate having a plurality of entrance apertures therein, which apertures are in alignment with an exit aperture on the opposite side 6 ity of apertures forming means for collecting said beam of reflected electrons.
  • said means for producing and projecting a beam of electrons comprises a cathode disposed adjacent to, and in alignment with, the plurality of entrance apertures of said plate.
  • said means for producing and projecting a beam of electrons comprises a source of electrons, a control electrode disposed'intermediate said source of electrons and said cavity resonator, said control electrode having a plurality of apertures therein, which apertures are in register with said entrance apertures.
  • said cavity resonator comprises a co-axial line resonator, including an outer member having an entrance aperture and an exit aperture in the wall thereof, said apertures being in diametric alignment, and an inner member having a passage therethrough in alignment with said entrance and said exit apertures.
  • said cavity resonator comprises a co-axial line resonator, including an outer member having an entrance aperture and an exit aperture in the wall thereof, said apertures being in diametric alignment and an inner member having a passage therethrough in alignment with said entrance aperture and said exit aperture, and wherein said means for reflecting said beam of electrons comprises a reflector electrode, and said means for producin a field and for deflecting said beam of electrons, comprises a pair of deflecting electrodes parallel to and spaced from each other, and positioned intermediate said coaxial line resonator and said reflector electrode, said deflecting electrodes also being positioned on opposite sides of the path of said beam of electrons.
  • said cavity resonator comprises a co-axial line resonator, including an outer member having a plurality of entrance apertures and an exit aperture in the wall thereof, said entrance apertures being in diametric alignment with said exit aperture, and an inner member having a passage therethrough in alignment with said entrance and exit apertures.
  • said cavity resonator comprises a co-axial line resonator, includin an outer member having a plurality of entrance apertures and an exit aperture in the wall thereof, said entrance apertures being in diametric alignment with said exit aperture, and an inner member having a passage therethrough in alignment with said entrance and said exit apertures, and wherein the means for producing and projecting a beam of electrons comprises a cathode disposed adjacent to and in alignment with said apertures of said co-axial line resonator, and a control electrode disposed intermediate said cathode and said coaxial line resonator, said control electrode having a plurality of apertures therein, said apertures being in register with said entrance apertures.
  • An electron discharge apparatus of the electron velocity modulated type comprising a cavity resonator having apertures therein, means adjacent an aperture in said cavity resonator and external thereto, for producing and projecting a beam of electrons along a first path through said cavity resonator and a pair of said apertures, means adjacent the aperture in said cavity reso- 8 n'ator from which said beam of electronsemerges, for deflecting and reflecting said beam of elec- REFERENCES CITED tron along a second path extending i t i
  • the following references are of record in the cavity resonator and through an aperture therein, file of this P t: means for collecting said reflecting beam of eiec- 5 UNITED STATES PATENTS trons, which means are positioned mtermediate said last mentioned aperture and said means for Number Name t producing and projecting said beam of electrons.

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US588207A 1943-04-19 1945-04-13 Electron discharge device of the velocity modulation type Expired - Lifetime US2462087A (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2717327A (en) * 1947-01-17 1955-09-06 Int Standard Electric Corp Velocity modulation devices
US2786943A (en) * 1953-07-10 1957-03-26 Zenith Radio Corp Electron discharge devices
US3611166A (en) * 1967-11-21 1971-10-05 Csf Accelerator for relativistic electrons

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2075379A (en) * 1935-03-13 1937-03-30 Farnsworth Television Inc Time delay oscillator
US2170219A (en) * 1936-10-16 1939-08-22 Telefunken Gmbh Ultra high frequency oscillator
US2250511A (en) * 1938-09-02 1941-07-29 Univ Leland Stanford Junior Oscillator stabilization system
US2320860A (en) * 1939-12-22 1943-06-01 Int Standard Electric Corp Electron discharge apparatus
USRE22506E (en) * 1937-07-14 1944-06-27 Electrical discharge device

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2075379A (en) * 1935-03-13 1937-03-30 Farnsworth Television Inc Time delay oscillator
US2170219A (en) * 1936-10-16 1939-08-22 Telefunken Gmbh Ultra high frequency oscillator
USRE22506E (en) * 1937-07-14 1944-06-27 Electrical discharge device
US2250511A (en) * 1938-09-02 1941-07-29 Univ Leland Stanford Junior Oscillator stabilization system
US2320860A (en) * 1939-12-22 1943-06-01 Int Standard Electric Corp Electron discharge apparatus

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2717327A (en) * 1947-01-17 1955-09-06 Int Standard Electric Corp Velocity modulation devices
US2786943A (en) * 1953-07-10 1957-03-26 Zenith Radio Corp Electron discharge devices
US3611166A (en) * 1967-11-21 1971-10-05 Csf Accelerator for relativistic electrons

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Publication number Publication date
FR932279A (fr) 1948-03-17

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